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1973 Riviera Overheating


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My Riv runs about 210+ after an hour on the expressway. Scheduled radiator flush this week (never been done in the year I've had the car), but what else might be a remedy if that's unsuccessful?

 

May be the thermostat, which they will also check, so let's move past that.

 

A guy I know (not a mechanic) said it may be possible to add another core to the radiator. The mechanic said he'd never heard of doing that.

 

Also heard of adding another blade to the fan or two fans, larger fan, etc. Don't know if any of those are possible.

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20 minutes ago, Golden73 said:

radiator flush

Don"t let them tell you that flushing will fix it.  The only way to service a radiator is to disassemble and rod out and if it cannot stand up to that then a new core.

And 210* is not too hot.  With a good pressure cap it will go over 250* before boiling over.  If the temperature rises in traffic consider  a new fan clutch.

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15 minutes ago, old-tank said:

Don"t let them tell you that flushing will fix it.  The only way to service a radiator is to disassemble and rod out and if it cannot stand up to that then a new core.

And 210* is not too hot.  With a good pressure cap it will go over 250* before boiling over.  If the temperature rises in traffic consider  a new fan clutch.

 

They didn't say it. I'm just assuming it hadn't been done ever, since the car sat for most of its life, with only 28K miles that's only 500+/- a year and I'm trying to catch up on maintenance. Also assuming it could be something else. I left it open for the repair shop, which is why I'm asking here, trying to get several opinions so I don't spend money on needless stuff. As for the actual temp, could be the temp gauge is installed incorrectly (I didn't do it) and giving me a false reading. I read somewhere that the normal operating temp of that motor is about 180, so 210 - 220 is indeed high (although not fatal), but the 180 normal number could also be wrong. I have a couple repair manuals but I haven't yet been able to find the temp range that recommends.

 

I'll mention the fan clutch and the heat riser valve on the exhaust manifold, as well.

 

A couple other people I know have mid-60's Buicks with similar concerns so I'm their guinea pig, I guess.

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If a radiator is clogged beyond repair you could have it "re-cored" and, at that time,  install a core with an extra "row".   Not certain how many rows you already have.   Many higher end big block cars will have come with a 3 core radiator.  If the tanks on the edges of the radiator are wide enough you could go to a 4 row core.   But this is a very expensive job and you'd be better served to make sure other things are working right. 

 

One possible culprit may be the distributor vacuum advance.  

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2 hours ago, Golden73 said:

My Riv runs about 210+ after an hour on the expressway. Scheduled radiator flush this week (never been done in the year I've had the car), but what else might be a remedy if that's unsuccessful?

 

May be the thermostat, which they will also check, so let's move past that.

 

A guy I know (not a mechanic) said it may be possible to add another core to the radiator. The mechanic said he'd never heard of doing that.

 

Also heard of adding another blade to the fan or two fans, larger fan, etc. Don't know if any of those are possible.

  If your overheating concerns only occur at speed on the highway you have narrowed your troubleshooting tree by %50...so dispense with concerns which involve air flow, like fans, clutches, shrouds, etc because you are getting plenty of air flow at highway speed. With symptoms such as yours, cooling system efficiency should be your focus, such as drive belts, radiator, thermostat, water pump.

  It is possible to add an extra row of cooling (generally termed 4 row core) if your present tanks have the physical space or more efficient cores, compared to your original style, are available.

  210 degrees under load, at speed on a hot day is not that bad, if accurate...I would guess if your original radiator can survive a rodding out your temp will fall into an acceptable range.

Tom Mooney

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If you have a "creeping heat" issue, where the temp rises slowly, even at highway speeds, then the bottom of the radiator core is probably "sedimented" somewhat, which effectrively makes it a bit smaller in size.  An IR "heatr gun" can be a quick and effective way to check for this!  For about $30.00 USD as some of the "freight"/tool companies.

 

At highway speeds, the fan clutch should be "idling" and letting the air coming through the radiator spin it somewhat.  Agreed, with the factory 195 degree F thermostat sped, 210 is a normal temp for ANY ambient temperature.  Which might bre just one needle-width past the center mark on the temp gauge, by observation.  I know, we lke to see those needles be on the low sisde of that, but that little bit past, to the right of the mark, is fine.

 

Personally, I've had much bretter long-term luck just getting a new, OEM-spec fadiator rather than a re-core.  www.rockauto.com canm be a good resource from which to check pricing of such.  In many cases, even the base a/c radiatore (or non-a/c HD radiator) in many GM vehicles is a two-core radiator.  Yet the tanks are wide enough for a three-row core to be installed between them.  With ANY radiator re-core, make SURE they use an OEM-level solder to put things together with.  The solders might look the same, but they certainly do NOT act the same after about two years, from my experiences.  Which means you might ask nearby body shops whom they use for radiator repairs/sourcing.

 

ONE other bit of maintenance could be doing a full "block flush" of the cooling system.  Which means all of the core plugs in teh block are knocked out, teh block's coolant passages are flushed out, then new ones installed, with fresh coolant.  Sediment will accumulate at the lowest points in the cooling system, which is usually at the rear of teh engine block.  Quite messy and labor intensive, but might cure some problems before they might get any worse!

 

Enjoy!

NTX5467

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Another option to consider might be an aluminum radiator.  For example, Griffin produces the Exact Fit series radiators including made for collector vehicles such as your Riviera.  They offer OEM fitment and are made in the USA.  Griffin has been in the business 30 years.  They are not inexpensive although cool very well.  Aluminum radiators can easily be painted black for the OEM appearance. 

 

I have no relationship with the company.

 

Jim Vesely

BCA # 39477

ROA # 7437

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In that orientation, rockauto.com shows some Liland Global rull-aluminum radiators for that application (AND many others!) at about what the old copper/brass items used to cost, or a bit less.  Just need some satin black paint on them, if desired.  Also many of the newer composit-tank/aluminum core OEM-style radiators, too, at VERY reasonable costs.  But IF cosmetics are important, then a quality radiator shop will be needed.

 

From my own experiences, the new OEM-style composite radiators are much more efficient than the older copper/brass items ever could be.  Much lighter in physical weight and generally hold a little less fluid, if that matters.  On a spring day, after putting an AC-Delco composite replacement radiator in my '77 Camaro, it took 45 minutes for the 180 degree thermostat to open fully.  I was impressed!  PLUS a much lower price, back then, compared to the Modine 3-row that was in it then.  For me, on that care, no need to go backward!

 

Griffin and a few other brands were the first with universal fit, with the OEM-fit items coming more recently, but they aren't the only choice any more.  FWIW

 

Just some thoughts,

NTX5467

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So after all your input I decided to just have the mechanic test the coolant levels/quality and see where it is.

 

Naturally, it's sitting at the shop until the window motor gets delivered, which isn't going to be quick, unfortunately.

 

What a shitty year.

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On 8/15/2020 at 6:12 PM, Golden73 said:

A guy I know (not a mechanic) said it may be possible to add another core to the radiator. The mechanic said he'd never heard of doing that.

Also heard of adding another blade to the fan or two fans, larger fan, etc. Don't know if any of those are possible.

 

I have a 1973 Riviera and have never had a heating problem,

and those cars were considered reliable in their day.

If you figure that the original systems were properly engineered,

there should be no need to modify them with a different radiator

or a different fan.  Those would be simply masking the problem.

 

Somewhere within the original equipment is your solution--

getting everything working as originally designed.

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You might try squeezing the lower radiator hose to feel if there is a spring inside. Someone may have replaced the old hose with one that didn't have one. Or the 50 year old hose gave it's spring up to Mother Nature.

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